This invention relates to a guide device of the type used on a base.
For some time, such guide devices have been provided with air bearings. Thus, German Patent DE-PS No. 12 58 671 describes a guide device in which air bearings are provided in conjunction with rigid guide surfaces which are bias tensioned by magnets.
West German DE-OS No. 23 46 693 describes a machine guide in which a guide surface is provided with a separately constructed component which supplies the air bearing, this component being secured against longitudinal displacement.
West German DE-OS No. 30 23 837 discloses another airborne machine guide, the bearing of which is said to present better operating properties, in particular higher loadability and better stability.
All of these prior art devices have in common the feature that the direction of movement of the elements to be guided (for example, a machine slide piece) must be established at the outset. Subsequent changes of the direction or the working range cannot be accommodated. Such a fixing of the orientation of the guiding direction and the working range is, for machines of the type described, logical and sufficient. However, other machines such as measuring machines are often used in a more versatile manner in which it is often quite cumbersome to use fixed direction or working length guides. This is because such guides severely restrict the versatility of use of the measuring instrument.
However, it is precisely in the field of high precision measuring equipment that a high degree of specialized knowledge and manufacturing precision are required to produce suitable measuring instruments. The acquisition of such instruments, therefore, is associated with high costs for the user.
For this reason, measuring machines should be made to operate in as versatile a manner as possible. Known prior art guide devices that are preferably used in measuring machines, however, do not provide the required high degree of versatility. This is because, as mentioned at the outset, the directions of movement and the measuring range are both severely restricted. For this reason, movements in differing coordinate directions in differing spacings to the base of the measuring plane are required. With this approach either the accuracy of measurement is impaired or alternately, compensation calculations must be used to eliminate errors.